Various types of bonding materials are useful in the fabrication of filled synthetic polymer compositions. Certain of these synthetic polymer compositions have been used for fabricating flexible magnetic recording media. Another application of importance, especially from a commercial point of view, involves fabricating abrasive articles. In both of these areas of use, the interactions between the inorganic filler and binder can effect critical characteristics of the final composition, and therefore, its applicability for practical use. This is especially important since in both magnetic recording media applications and abrasive articles, high filler loading is employed which makes it necessary to have strong interactions between the filler particles and binder.
In addition, high density recording requires tape coatings to be fabricated with increasingly smaller magnetic particles. However, current binder systems do not adequately address the need for optimized binder-filler interaction and coating mechanical requirements. In fact, current binder systems produce excessive debris and contamination of the recording interface. For instance, it has been particularly difficult to achieve useful reinforcement of conventional binders when filled with stabilized iron metal particles, or of aluminum oxide (alumina) particles, typically included along with iron metal or other non-abrasive particulate media, as head cleaning agents. In addition, due to the lack of significant chemical interaction with the oxide protective layer on these particles, the results appear to indicate considerable sensitivity to not only the source and type of particle, but also variations from within the same lot of material in the case of iron metal powders.
In fact, as compared to chromium dioxide particles, the interaction of iron and similar particles with various binders is significantly less. For example, polyurethanes, which are quite suitable when used with chromium dioxide particles, are not acceptable when used as the binder for iron and iron oxide particles.